1. Technical Field
The invention concerns an examination chair for gynecological and urological examinations including a chair portion with a seat and a backrest as well as a supporting column with a column head height adjustable by way of an adjusting drive, on which column head the chair portion is arranged, with means being provided for adjusting the seat and the backrest relative to the supporting column.
2. Background of the Prior Art
From DE 25 08 034 C2 an examination chair for gynecological and urological examinations is known in which a chair portion with a backrest is pivotally connected with a supporting frame for movement about a fixed tilt axis and is pivoted in its entirety with the help of an adjusting cylinder. The adjusting cylinder is connected on one side to the support frame and on the other side directly to the backrest of the chair portion. The seat as to its position relative to the backrest remains unchanged, but the seat can be swung downwardly when the backrest is positioned nearly horizontally. A simultaneous adjustment of the backrest and the seat relative to the supporting column and relative to one another is not provided.
In the case of operating tables, it is known to adjust individual sections of the patient support surface relative to one another by individual drives. This requires a relatively high technical expense.
The invention has as its basic object the provision of an examination chair of the previously mentioned kind whereby with relatively small technical expense the backrest and seat can be synchronously adjusted relative to the supporting column and relative to one another.
This object is solved in accordance with the invention in that the backrest is pivotably supported on the column for movement about a horizontal first pivot axis and is so pivoted by a pivot drive, that the seat is pivotably supported on the backrest for pivotal movement about a second pivot axis parallel to the first pivot axis and is further connected with the backrest by means of a four-corner linkage which includes the two pivot axes, a link axis fixed relative to the seat, and a free link axis, and wherein the link of the four-corner linkage which connects the first pivot axis with the free link axis is a first lever arm of a two arm control lever, which first lever arm cooperates with a stop fixed to the column for establishing a fundamental position of the seat, while the second lever arm of the control lever for adjustment of the seat is designed for cooperation with a stop fixed to the backrest.
The fundamental position of the seat is for example a horizontal position. Relative to this fundamental position of the seat, the backrest can be adjusted through a given angular range, with the seat because of its connection with the backrest through the four-corner linkage being shifted in its fundamental horizontal position. Not until the backrest is tilted rearwardly through a given angle does the stop fixed to the backrest come into engagement with the second lever arm of the control lever so as to move, through the control lever and the four-corner linkage the seat synchronously with the backrest.
A preferred embodiment provides that the pivotal movement of the control lever from its position which corresponds to the fundamental position of the seat is limited by a second stop fixed to the column and that the stop fixed to the backrest is pivotal against a spring force. This gives the possibility of holding the seat in a given pivoted position by means of the stop fixed to the column, while the backrest can be moved beyond this position by the pivoting of the stop fixed to the backrest, so that the seat and the backrest can, for example, be brought into an almost stretched out position.
The pivoting drive is preferably a linear drive, for example a spindle drive, one end of which is connected with the column head and the other end of which is pivotally connected with the backrest.
In this way it is possible with a single pivoting drive to adjust the seat and backrest to different positions relative to the supporting column and relative to one another.